//信息类型枚举类型
enum MessageType {SYSTEM,PUBLIC,CHAT,GROUP }
//聊天数据
class MessageData{
  //头像
  String avatar;
  //主标题
  String title;
  //子标题
  String subTitle;
  //信息时间
  DateTime time;
  //信息类型
  MessageType type;

  MessageData(this.avatar,this.title,this.subTitle,this.time,this.type);
}

List<MessageData> messageData =[
  new MessageData('https://cna.bbkz.net/forum/attachment.php?s=f986851772f4bb9bc15d65aa7b208d75&attachmentid=2235070&d=1512899364',
  'fly',
  '今天一起去玩',
  new DateTime.now(),
  MessageType.CHAT
  ),
  new MessageData('http://static.oneplus.cn/data/attachment/forum/201708/02/223444ne33cshchchcxhpv.jpg',
  'OnePlus',
  '一加7 2999元',
  new DateTime.now(),
  MessageType.CHAT
  ),
  //添加更多聊天数据
];